1. Field of the Invention
The present invention relates to a rewritable optical recording media and more particularly to a defect area management method of an optical recording medium.
2. Discussion of Related Art
A rewritable optical disc generally includes a Rewritable Compact Disc (CD-RW) and a Rewritable Digital Versatile Disc (DVD-RW, DVD-RAM and DVD+RW).
The rewritable optical disc performs repeated operations for recording/playback of information thereon. However, by the repeated operations, a mixture ratio of the mixture forming a recording layer for recording the information on the optical disc is changed from an initial mixture ratio thereof. Thus, the inherent characteristic of the optical disc is not maintained, thereby generating errors during recording/playback of information. This is commonly known as degradation.
The area where degradation occurs is designated as a defect area which appears upon the implementation of formatting, recording and playback commands of the optical disc. The defect area of rewritable optical discs may also be generated due to scratches on the surface, particles such as dust, and errors during manufacturing. Therefore, to prevent data from being recorded on or playback from defect areas of the optical disc, an effective management system for the defect area is necessary.
As shown in FIG. 1, a management system for defect areas on an optical disc is achieved by allocating a defect management area (DMA) in a lead-in area and a lead-out area of the optical disc. Also, a data area is managed in groups, each having a user area for actual recording of data and a spare area for use in case of defects in the user area.
Typically, one disc (e.g. DVD-RAM) has four DMAs, two in the lead-in area and two in the lead-out area. Since managing defect area is important, the same data are held in all four DMAs for data protection. Each DMA includes two blocks and of 32 sectors, wherein one block consists of 16 sectors. The first block (DDS/PDL block) of each DMA includes a disc definition structure (DDS) and a primary defect list (PDL), and the second block (SDL block) includes a secondary defect list (SDL)
More specifically, the PDL represents a primary defect data storage area, and the SDL represents a secondary defect data storage area. The PDL stores entries of all defective sectors generated during manufacture and identified during formatting such as initialization or re-initialization. Each entry, as shown in FIG. 2A, includes a sector number corresponding to a defective sector and an entry type. The sector number is listed in the carry order, and the entry type is listed by the origin of the defective sector.
For example, the entry type is divided into a P-list, a G1-list and a G2-list, as defined by the disc manufacturer. More particularly, the defective sectors generated during the manufacture of the disc are stored in the P-list. The defective sectors found by a certification process during a formatting of a disc are in the G1-list, and the defective sectors converted from the SDL without any certification process are in the G2-list.
On the other hand, the SDL is arranged in block units and holds entries of either defective areas which may be generated after initialization or defective areas which cannot be entered in the PDL during initialization. Each entry of the SDL as shown in FIG. 2B includes an area storing the sector number of a first sector of the block having a defective sector, and an area holding the sector number of a first sector of a replacement block. Additionally, 1 bit is assigned for the FRM. A FRM bit value of xe2x80x980bxe2x80x99 indicates that a replacement block is assigned and the block is in a functional state. Contrarily, a FRM value of xe2x80x981bxe2x80x99 indicates that either a replacement block is not assigned or a defect on the replacement block exists.
The initializing method of a disc is divided into an initialization formatting and a re-initialization formatting. The re-initialization formatting method is further classified into a full formatting similar to the initialization formatting, a partial certification for a partial initialization, and a conversion of SDL to G2-list by which the SDL is transferred to the G2-list of the PDL without the certification process in order to reduce the formatting time. The P-list remains unchanged after the completion of formatting but defective blocks of the SDL are stored as defective sectors in the G2-list. Thus, the G2-list may include defective sectors as well as non-defective sectors.
As shown in FIG. 3A, in the partial certification, the sectors on the P-list and G1-list prior to the formatting remain on the P-list and the G1-list after the completion of formatting. However, the defective blocks on the old G2-list and old SDL undergo a certification process. Namely, the entries of the G2 list and the SDL are erased, and defective sectors found during the certification process are listed in the G1-list.
This is because non-defective sectors are also entered as part of the defective block on the G2-list and the SDL. At this time, if an overflow occurs on the G1-list, the remaining entries are listed on the new SDL and null data is inserted into the G2-list. An overflow may occur because as the PDL is comprised of 15 fixed sectors in the DMA, the number of entries which is registered in the PDL is restricted.
The conversion format of the SDL to the G2-list without certification is shown in FIG. 3B. The sectors in the P-list, G1-list and G2-list prior to the formatting remain without change in the P-list, G1-list and G2-list after the completion of the formatting. The entries on the SDL are converted into 16 PDL entries and are then listed in the G2-list. At this time, if an overflow occurs on the G2-list, the remaining entries which cannot be entered in the G2-list, are listed on the new SDL.
On the other hand, defective areas in the data area (i.e. defective sectors or defective blocks) are replaced with new non-defective sectors or blocks, respectively by slipping replacement or linear replacement.
The slipping replacement is utilized when a defective area or sector is listed in the PDL. As shown in FIG. 4A, if defective sectors m and n, corresponding to sectors in the user area, are recorded in the PDL, such defective sectors are replaced by the next available sector. By replacing the defective sectors by subsequent available sectors, data is written to a normal sector.
As a result, the user area into which data is written slips and occupies the spare area in the amount equivalent to the defective sectors. For example, if two defective sectors are recorded on the P-list or the G1-list of a PDL, the data is pushed back two sectors into the spare area and is then recorded.
The linear replacement is utilized when a defective area or block is recorded in the SDL. As shown in FIG. 4B, if defective sectors m and n, corresponding to sectors in either the user or spare area, are recorded on the SDL, such defective blocks are replaced by normal blocks in the spare area and the data to be recorded in the defective block are recorded in an assigned spare area. To achieve the replacement, a physical sector number (PSN) assigned to a defective block remains, while a logical sector number (LSN) is moved to the replacement block along with the data to be recorded. Linear replacement is effective for non real-time processing of data.
More particularly, if a replacement block recorded in the SDL has been defective, a direct pointer method is applied in the data registration of the SDL. The defective replacement block is changed into a new replacement block by the application of the direct pointer method. Thus, the entries on the SDL where the defected replacement block has been entered have the sector number of a first sector of the new replacement block.
FIGS. 5A to 5I show an optical disc structure as discussed above. FIG. 5A shows defect areas appearing on the disc and a management state for the defect areas, and FIGS. 5B to 5I show each state indicated in FIG. 5A. In other words, FIG. 5B shows that the disc in FIG. 5A is modeled in a block (=16 sectors) units, and FIG. 5C shows that one defective sector is recorded on the P-list or the G1-list of the PDL. FIG. 5D shows that all 16 sectors of one defective block are recorded on the G2-list of the PDL, and FIG. 5E shows that a block with a defective sector is recorded on the SDL. The information (1, sblkA, 0) is a SDL entry, in which the entries correspond to the FRM, the sector number of the first sector of a defective block, and the sector number of the first sector of a replacement block.
FIG. 5F shows that a defective block of the user area is replaced with the block in the spare area, and is then recorded as an entry of the SDL. The information (0, sblkB, sblkD) indicates that a non-defective block has been assigned, and the data to be recorded on the defective block sblkB of the user area is recorded on the replacement block sblkD of the spare area.
FIG. 5G shows an SDL entry which indicates that an assigned replacement block sblkC of the spare area for the defective block sblkA of the user area is also defective. Therefore, by the application of the direct pointer method, the defective replacement block sblkC is changed into a new replacement block sblkE and the SDL entries are corrected with the information of the new replacement block sblkE. FIG. 5H shows the correcting process of FIG. 5G. At this time, the information on the defective block sblkC of the spare area is erased. In other words, the information remaining on the SDL is (0, sblkA, sblkE) and (0, sblkB, sblkD).
Also, the number of logical sectors on the disc is fixed. Thus, during the re-initialization formatting of the disc, especially during the partial conversion or the conversion of SDL into the G2-list, the spare area can be assigned to the user area by the slipping method. For example, when a disc as shown in FIG. 5A is re-initialized for converting the SDL to the G2-list of the PDL, there is no information on defective blocks of the spare area. Accordingly, considering only the fixed number of logical sectors, irrespective of the defective blocks of the spare area, the user area is pushed into the spare area by the defect area of the user area (or defective sector or block of the user area which is newly registered on the PDL,) such that the user area is assigned as shown in FIG. 5I.
In other words, although block sblkC of the spare area is defective, it is within the normal block of the user area because the information of the block sblkC does not exist as an entry of the SDL.
On the other hand, many defective area management methods for real time recording have been presented. One of such methods is a skipping method in which the linear replacement is not performed when using the SDL, but a data of an encountered defective block is written on a good block subsequent to the defective block as in the slipping replacement. Namely, if the real time recording of input data is not required during the use of the SDL, the linear replacement method is used as shown in FIG. 6A. However, if the real time recording is required, the skipping method is used as shown in FIG. 6C.
Referring to FIG. 6A, assume that blocks sblkA and sblkB of the user area are defective and the blocks sblkC and sblkE of the spare block replacing the defective blocks sblkA and sblkB are also defective. The block sblkA is replaced with the block sblkF of the spare area and block sblkB is replaced with block sblkD of the spare area. As a result, the remaining entries on the SDL have the information (0, sblkA, sblkF) and (0, sblkB, sblkD), shown in FIG. 6B. The information on defective blocks sblkC and sblkE of the spare area is not stored and is thus lost.
Thereafter, if data is rewritten by the skipping method as shown in FIG. 6C for the real time recording on the disc without re-initialization formatting, the information on the replacement blocks sblkD, sblkF of the spare area is not required as entries of the SDL. Furthermore, if the data recorded by the skipping method is to be played back, the data should also be played back by the skipping method.
At this time, if the information on the replacement blocks of the spare area exists as entries of the SDL, the data is undesirably played back in the same manner as the linear replacement method. Thus, the information on the replacement blocks of the spare area should be erased as entries of the SDL.
If the conversion formatting of the SDL into the G2-list of the PDL is performed on the disc where the data is recorded as shown in FIG. 6C, the user area is also slipped into the spare area by the defective blocks of the user area such that the user area is assigned as shown in FIG. 6D. The user area is slipped irrespective of the defective blocks of the spare area because there is no information on the spare area.
In the same manner as above, although block sblkC of the spare area is defective, it is within the normal block of the user area because the information of the block sblkC does not exist as an entry of the SDL.
Thereafter, if the data is written without any certification process of the re-initialization formatting in the skipping or linear replacement manner, the defective block sblkC is extended to the normal block of the user area, such that the data is written. At this time, when recording the data without any certification, the SDL is not created upon the data recording, but it is created upon the playback of data after the recording.
This may result in generation of errors during playback of data. Since block sblkC where the data is already recorded is defective, the data on block sblkC cannot be read during the playback of data. If the data is not read, the data recorded on the block is lost. More particularly, if an important data, such as file system information is recorded on block sblkC, the information loss will have a serious influence to a user.
Accordingly, an object of the present invention is to solve at least the problems and disadvantages of the related art.
An object of the invention is to provide a defect area management method of an optical recording medium which can store information of a defective spare block in a defect management area to thereby prevent errors generation.
Another object of the invention is to provide a defect area management method of an optical recording medium which can enter information of a defective replacement block contained in a user area on a defect management area upon re-initialization formatting to thereby prevent generation of errors.
Still another object of the invention is to provide a defect area management method of an optical recording medium which can enter information of a defective spare block on a secondary defect list before re-initialization formatting to thereby prevent errors from being generated after the re-initialization formatting.
Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objects and advantages of the invention may be realized and attained as particularly pointed out in the appended claims.
To achieve the objects and in accordance with the purposes of the invention, as embodied and broadly described herein, a defect area management method of an optical recording medium comprises storing on a defect management area information of defective block in the user area upon formatting and storing information of defective replacement blocks within a newly defined user area according to slipping.
The information of defective replacement blocks in the user area is entered in a primary defect list, if overflow is not generated in the defect management area. On the other hand, the information of defective replacement blocks which is not stored in the primary defect list is entered in a secondary defect list, if overflow occurs in the defect management area.
The information of defective blocks in the user area is also registered on the secondary defect list, and information of defective replacement blocks is inferred from the replacement blocks registered in the secondary defect list.
After the information of defective blocks in the user area is converted into the primary defect list of the defect management area, the information of defective blocks within a spare area may be converted into the primary defect list. Also, after the information of defective blocks within the spare area is converted into the primary defect list of the defect management area, the information of defective blocks within the user area may be converted into the primary defect list. Furthermore, the information of defective blocks within the user area and the information of defective block within the replacement area may be converted alternately into the primary defect list of the defect management area.
An overflow may be generated when information of defective blocks in the user area registered on the secondary defect list cannot be registered in the primary defect list during formatting. An overflow may also be generated when information of defective blocks within the spare area cannot be registered in the primary defect list during formatting.
If an overflow occurs on the primary defect list upon formatting where defective blocks of the secondary defect list is converted into the primary defect list without certification, the information of defective blocks within the spare area is not stored. If an overflow occurs on the primary defect list upon formatting where defective blocks registered on the secondary defect list is converted into the primary defect list through a certification process, the position information of defective blocks in a spare area not utilized is stored in a new secondary defect list. However, if an overflow is generated on the primary defect list, the position information of defective blocks in the spare area registered on the new secondary defect list, is not stored.
In the preferred embodiment, the certification process should be applied only to defective blocks of the spare area during formatting.
Upon data recording, a determination may be made whether a replacement block is defective and if defective, the information of defective replacement block is stored in the secondary defect list. The information is converted into the primary defect list, upon formatting.
In the preferred embodiment, only information of defective replacement blocks is stored in the secondary defect list during data recording. The information of a block to be newly replaced is not stored.
According to another aspect of the present invention, a defect area management method of an optical recording medium comprises storing in a primary defect list the information of defective blocks registered on a secondary defect list upon formatting, and storing in the primary defect list the information of defective replacement blocks in a user area. The information of defective replacement blocks in the user area which is not stored in the primary defect list is registered in a new secondary defect list, if overflow occurs in the primary defect list.
According to yet another aspect of the present invention, a defect area management method of an optical recording medium comprises determining whether a replacement block is defective, if defective, storing the information of the defective replacement block in a secondary defect list; and storing the information of the defective replacement block registered on the secondary defect list in a primary defect list upon formatting. If an overflow occurs in the primary defect list upon formatting, the information of defective replacement blocks, which is not converted into the primary defect list, is stored in a new secondary defect list.